Particulate matter (PM) comprises a significant portion of air pollution. Particles in the range of 0.01 to 1.0 micron (PM1.0) are of particular concern, as these deposit in the lung exponentially with decreasing size. Within the alveoli, PM has the potential to initiate inflammatory and immune responses. Particles <1.0 micron are a heterogeneous mixture based on source generation and composition. Studies have shown that particle number, irrespective of composition is critical for macrophage-mediated alveolar clearance due to an "avalanche" effect. Understanding the potential impact or particles on human health is hampered by our ability to accurately characterize average, peak, and cumulative personal exposures in population studies. The proposed study will develop a miniature personal sensor for the detection of PM1.0 that will be field worthy and child friendly. The resulting will enable numerous applications by providing an integrated cyclone, saturator, condenser, and optical detector package consuming only milliwatts of electrical power, and functioning independent of physical orientation and a normal child's activity. The sensor will also have wireless function and position tagging using the advanced information transfer technology developed by NASA, Thus, this study is unique due to the miniature size of the sensor package allowing for constant wear during the daily activities of young children, the ability to monitor PM1.0, and the incorporation of the GPS device which will enable the location of specific exposures to be recorded. The need for personal monitors capable of measuring micro-environmental PM exposure is especially relevant where exposure to many pollutants is highly variable often across short distances, particularly in urban areas, and dependent upon personal activity patterns.